DCT

3:19-cv-00970

Orthopaedic Hospital v. DJO Global Inc

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 3:19-cv-00970, S.D. Cal., 03/08/2021
  • Venue Allegations: Plaintiff alleges venue is proper in the Southern District of California because Encore Medical has a regular and established place of business in the district and has allegedly committed acts of infringement there.
  • Core Dispute: Plaintiff alleges that Defendant’s orthopedic joint replacement systems, which incorporate a specialized polyethylene, are manufactured using patented methods that create wear- and oxidation-resistant implants.
  • Technical Context: The technology concerns ultra-high molecular weight polyethylene (UHMWPE), a material critical for the longevity of artificial joints, where reducing wear and oxidative degradation is a key factor in preventing implant failure.
  • Key Procedural History: The complaint notes that two of the patents-in-suit (the '710 and '347 patents) were previously asserted against DePuy Orthopaedics. In that litigation, the Patent Trial and Appeal Board (PTAB) denied institution of inter partes review (IPR) petitions filed by DePuy, finding DePuy had not established a reasonable likelihood of prevailing. That litigation was voluntarily dismissed by stipulation in November 2018.

Case Timeline

Date Event
2000-04-27 Earliest Patent Priority Date for all Patents-in-Suit
2011-01-01 Alleged launch of Accused E+ Products (approximate)
2014-02-24 Alleged notice to Encore of patents via DePuy Litigation filing
2014-02-25 U.S. Patent No. 8,658,710 Issues
2014-08-05 U.S. Patent No. 8,796,347 Issues
2015-10-13 U.S. Patent No. 9,155,817 Issues
2016-01-26 U.S. Patent No. 9,242,025 Issues
2016-04-05 U.S. Patent No. 9,302,028 Issues
2018-11-16 DePuy Litigation voluntarily dismissed
2021-03-08 First Amended Complaint Filed

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 8,796,347 - Oxidation-Resistant and Wear-Resistant Polyethylenes for Human Joint Replacements and Methods for Making Them

  • Patent Identification: U.S. Patent No. 8,796,347, "Oxidation-Resistant and Wear-Resistant Polyethylenes for Human Joint Replacements and Methods for Making Them," issued August 5, 2014.

The Invention Explained

  • Problem Addressed: The patent’s background describes a dilemma in manufacturing polyethylene joint implants. While irradiation can be used to crosslink the polyethylene to improve wear resistance, this process generates free radicals. These free radicals react with oxygen, causing oxidation that degrades the material's mechanical properties and can lead to implant failure. Conventional post-irradiation thermal treatments (like remelting or annealing) to eliminate these free radicals also weaken the implant. (Compl. ¶¶42-48; ’347 Patent, col. 2:1-25).
  • The Patented Solution: The invention proposes a method that avoids this trade-off. It begins with an "oxidation-resistant" polyethylene, which is achieved by adding an antioxidant (such as vitamin E). This material is then irradiated at a dose higher than that used for standard sterilization (above 5 Mrad) to induce a high degree of crosslinking for wear resistance. The embedded antioxidant neutralizes the free radicals generated during irradiation, making a subsequent, potentially damaging, thermal treatment unnecessary. (Compl. ¶¶49-52; ’347 Patent, col. 6:55-7:24).
  • Technical Importance: This approach allows for the creation of a highly crosslinked, wear-resistant polyethylene implant that is also stabilized against the long-term oxidative degradation that previously plagued irradiated implants. (Compl. ¶¶50-52).

Key Claims at a Glance

  • Independent Claim Asserted: Claim 1.
  • Claim 1 Elements:
    • A method for producing a wear-resistant and oxidation resistant medical implant of a joint prosthesis, comprising the steps of:
    • (I) providing an oxidation-resistant medical implant of a joint prosthesis comprising a polyethylene component; and
    • (II) irradiating the oxidation-resistant medical implant at a radiation dose of above 5 Mrad to about 25 Mrad so as to crosslink the implant thereby improving its wear resistance, without thermally treating the implant to extinguish free radicals...
    • wherein the oxidation-resistant implant contains an antioxidant rendering it resistant to oxidation caused by free radicals generated by the irradiation of step (II).
  • The complaint reserves the right to assert additional claims. (Compl. ¶111).

U.S. Patent No. 8,658,710 - Oxidation-Resistant and Wear-Resistant Polyethylenes for Human Joint Replacements and Methods for Making Them

  • Patent Identification: U.S. Patent No. 8,658,710, "Oxidation-Resistant and Wear-Resistant Polyethylenes for Human Joint Replacements and Methods for Making Them," issued February 25, 2014.

The Invention Explained

  • Problem Addressed: As with the ’347 Patent, the invention addresses the need for a polyethylene implant that is both highly wear-resistant and resistant to oxidative degradation, without the structural weakening caused by traditional manufacturing trade-offs. (Compl. ¶¶42-48; ’710 Patent, col. 2:1-25).
  • The Patented Solution: The ’710 Patent claims a method similar to the ’347 Patent, involving the irradiation of an antioxidant-containing polyethylene without subsequent thermal treatment. However, the claims of the ’710 patent further define the resulting product by its specific, measurable physical characteristics. These properties—degree of swelling, molecular weight between crosslinks, and gel content—serve as objective metrics for a successfully crosslinked and stabilized material. (Compl. ¶152; ’710 Patent, col. 16:51-60).
  • Technical Importance: By claiming specific physical properties, the patent provides a quantitative fingerprint for the desired material structure, potentially offering a more precise definition of the invention than a purely process-based description. (Compl. ¶¶83, 162).

Key Claims at a Glance

  • Independent Claim Asserted: Claim 1.
  • Claim 1 Elements:
    • A method for producing a wear-resistant and oxidation resistant medical implant, comprising steps of:
    • (I) providing an oxidation-resistant medical implant... comprising a polyethylene component; and
    • (II) irradiating the... implant at a radiation dose of above 5 Mrad to about 25 Mrad... without thermally treating the implant...
    • wherein the oxidation-resistant implant contains an antioxidant...; and
    • the irradiated oxidation-resistant implant possesses the characteristics of: a degree of swelling of between about 1.7 to about 3.6; a molecular weight between crosslinks of between about 400 to about 3,500 g/mol; and a gel content of between about 95% to about 99%.
  • The complaint reserves the right to assert additional claims. (Compl. ¶150).

Multi-Patent Capsules

  • Patent Identification: U.S. Patent No. 9,155,817, "Oxidation-Resistant and Wear-Resistant Polyethylenes for Human Joint Replacements and Methods for Making Them," issued October 13, 2015.

  • Technology Synopsis: This patent claims a method similar to that of the ’347 Patent, involving high-dose irradiation of a polyethylene implant without a subsequent thermal treatment. The key distinction in asserted claim 1 is that it defines the resulting implant as being "highly resistant to oxidation caused by free radicals," rather than explicitly requiring the presence of an antioxidant. (Compl. ¶193).

  • Asserted Claims: Claim 1. (Compl. ¶191).

  • Accused Features: The manufacturing process for Defendant's E+ Products is alleged to meet the claim limitations. (Compl. ¶¶192, 198-205).

  • Patent Identification: U.S. Patent No. 9,242,025, "Oxidation-Resistant and Wear-Resistant Polyethylenes for Human Joint Replacements and Methods for Making Them," issued January 26, 2016.

  • Technology Synopsis: This patent claims a more detailed multi-step manufacturing method. The asserted claim includes steps for providing the antioxidant-containing material, forming it into an implant, packaging the implant, and sterilizing it while packaged, in addition to the high-dose irradiation step performed without subsequent thermal treatment. (Compl. ¶232).

  • Asserted Claims: Claim 1. (Compl. ¶230).

  • Accused Features: The comprehensive manufacturing, packaging, and sterilization process for Defendant's E+ Products is alleged to infringe. (Compl. ¶¶231, 237-254).

  • Patent Identification: U.S. Patent No. 9,302,028, "Oxidation-Resistant and Wear-Resistant Polyethylenes for Human Joint Replacements and Methods for Making Them," issued April 5, 2016.

  • Technology Synopsis: This patent's asserted claim is a hybrid of the concepts in the '347 and '710 patents. Like the '347 patent, it claims a method of irradiating an antioxidant-containing polyethylene without thermal treatment. Like the '710 patent, it further defines the resulting product by a physical property, but it is limited to only one: "a gel content of between about 95% to about 99%." (Compl. ¶281).

  • Asserted Claims: Claim 1. (Compl. ¶279).

  • Accused Features: The manufacturing process for Defendant's E+ Products is alleged to create a material with the claimed gel content. (Compl. ¶¶280, 294).

III. The Accused Instrumentality

Product Identification

Defendant Encore Medical’s orthopedic implant product lines that incorporate "E+ polyethylene," referred to collectively as the "E+ Products." (Compl. ¶¶75, 84). These include various knee, shoulder, and hip replacement systems. (Compl. ¶84). The complaint uses the 3DKnee™ System as a representative example. (Compl. ¶113).

Functionality and Market Context

  • The accused E+ polyethylene is a vitamin E blended, ultra-high molecular weight polyethylene used as a bearing surface in artificial joints. (Compl. ¶¶75-76). The complaint alleges its manufacturing process uses irradiation at doses ranging from above 5 Mrad up to about 7.5 Mrad to crosslink the material for improved wear resistance. (Compl. ¶¶77, 80). A key feature alleged in the complaint is that, because vitamin E is blended into the material to neutralize free radicals, the process "does not include an anneal or re-melt step." (Compl. ¶78). A diagram from Defendant's materials describes the E+ Polyethylene as "blended with vitamin E and moderately cross-linked to reduce oxidation and reduce long-term wear." (Compl. p. 13).
  • The complaint alleges that E+ polyethylene is an essential component across all of Encore Medical's orthopedic implant product lines and that a significant portion of its surgical implant revenue, reported as approximately $200 million in 2017, was derived from sales of E+ Products. (Compl. ¶¶84, 97-98).

IV. Analysis of Infringement Allegations

’347 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
(I) providing an oxidation-resistant medical implant of a joint prosthesis comprising a polyethylene component Encore Medical manufactures and provides an E+ polyethylene component, which it describes as being resistant to oxidation. ¶117-118 col. 6:60-64
(II) irradiating the oxidation-resistant medical implant at a radiation dose of above 5 Mrad to about 25 Mrad so as to crosslink the implant thereby improving its wear resistance Encore Medical's manufacturing process allegedly irradiates its E+ polyethylene at doses ranging from above 5 Mrad to about 15 Mrad to crosslink the material and improve wear resistance. ¶119-121 col. 7:4-11
without thermally treating the implant to extinguish free radicals in the irradiated and crosslinked implant Encore Medical's process allegedly omits an anneal or re-melt step, stating it is rendered unnecessary because vitamin E neutralizes free radicals. ¶122 col. 7:11-15
wherein the oxidation-resistant implant contains an antioxidant rendering it resistant to oxidation caused by free radicals The accused E+ Products contain vitamin E, an antioxidant, blended with the polyethylene resin. ¶123-124 col. 7:26-31

’710 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
(I) providing an oxidation-resistant medical implant... comprising a polyethylene component Encore Medical provides E+ polyethylene, which it markets as resistant to oxidation and long-term wear. ¶155-156 col. 6:60-64
(II) irradiating the oxidation-resistant medical implant at a radiation dose of above 5 Mrad to about 25 Mrad... without thermally treating the implant The E+ polyethylene is allegedly irradiated at doses from above 5 Mrad to about 7.5 Mrad without a subsequent anneal or re-melt step. ¶157-161, 163 col. 7:4-15
wherein the oxidation-resistant implant contains an antioxidant rendering it resistant to oxidation The accused E+ Products contain vitamin E blended into the polyethylene resin. A diagram of an e+ Glenoid product highlights its "moderately crosslinked vitamin E polyethylene" formulation. (Compl. p. 15). ¶164-165 col. 7:26-31
and the irradiated oxidation-resistant implant possesses the characteristics of: a degree of swelling of between about 1.7 to about 3.6; a molecular weight between crosslinks of between about 400 to about 3,500 g/mol; and a gel content of between about 95% to about 99% The complaint alleges on information and belief that the E+ polyethylene products possess these specific physical characteristics. ¶162 col. 13:1-12

Identified Points of Contention

  • Scope Questions: The core dispute may focus on the negative limitation "without thermally treating the implant." The parties may dispute whether any heating steps in the defendant's process, even if not explicitly labeled "annealing" or "remelting," could be construed as a "thermal treatment" for extinguishing free radicals, which would place the process outside the claim scope.
  • Technical Questions: For the ’710 Patent, a central evidentiary question will be whether the accused E+ polyethylene actually possesses the specific numerical ranges for swelling, molecular weight between crosslinks, and gel content required by the claim. The complaint alleges these properties exist "upon information and belief" (Compl. ¶162), suggesting this will be a subject of technical discovery and expert testimony.

V. Key Claim Terms for Construction

"without thermally treating the implant to extinguish free radicals" (’347 Patent, Claim 1; ’710 Patent, Claim 1)

  • Context and Importance: This negative limitation is central to the patents' claimed departure from prior art methods that used heat to remove free radicals. The complaint alleges Encore Medical's process omits this step (Compl. ¶¶78, 122). The case may turn on whether any part of the accused process could be characterized as a "thermal treatment" intended for this purpose. Practitioners may focus on this term because its scope will define the boundary between infringement and non-infringement.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification distinguishes the invention from prior art that used "remelting, or heating the implant above its melt temperature, and annealing, or heating the implant below its melt temperature" (Compl. ¶47; ’347 Patent, col. 6:45-54). A party could argue "thermally treating" should be construed broadly to cover any intentional application of heat post-irradiation that has the effect of extinguishing free radicals.
    • Evidence for a Narrower Interpretation: The specification consistently frames the avoided step in terms of specific, formal processes like "annealing or remelting" (’347 Patent, col. 7:1-3, 21-22). A party could argue that "thermally treating" should be limited to these specific, high-temperature processes and should not read on incidental or low-level heat exposure that might occur during other manufacturing stages.

"oxidation-resistant medical implant" (’347 Patent, Claim 1; ’710 Patent, Claim 1)

  • Context and Importance: The definition of "oxidation-resistant" is a threshold requirement for the starting material in the claimed methods. The dispute may involve how much resistance is required to qualify. The complaint relies on Defendant's own marketing, which describes the E+ polyethylene as having been "demonstrated to significantly reduce oxidation" (Compl. ¶¶116, 118).
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification does not set a strict numerical threshold for "oxidation-resistant." It describes the property functionally, for example, as being more resistant to oxidation than "reference preformed UHMWPE" (’347 Patent, col. 5:58-64). This could support a construction where any demonstrable improvement over conventional materials suffices.
    • Evidence for a Narrower Interpretation: The patent provides detailed examples comparing specific materials using quantitative oxidation measurements (e.g., ’347 Patent, FIG. 1; col. 15-16). A party could argue that the term should be limited by the context of these examples, requiring a specific, significant level of improvement in oxidation resistance as measured by the techniques described in the patent.

VI. Other Allegations

Indirect Infringement

The complaint alleges induced infringement for all asserted patents. The basis is that Encore Medical allegedly knows its E+ Products are made by the patented processes and induces customers (surgeons) and end-users (patients) to directly infringe under 35 U.S.C. § 271(g) by buying and using the products in the United States. This inducement is allegedly carried out through advertising, instructions for use (IFUs), product catalogues, and other marketing materials that tout the benefits of the E+ products. (Compl. ¶¶137-143, 178-184, 217-223, 267-272, 307-312).

Willful Infringement

Willfulness is alleged for all asserted patents. The complaint bases this on alleged pre-suit knowledge, asserting that Encore Medical had actual and constructive knowledge of the patents since at least their issue dates, and further had notice via Plaintiff's 2014 litigation against competitor DePuy involving the ’347 and ’710 patents. (Compl. ¶¶99-108, 128, 169).

VII. Analyst’s Conclusion: Key Questions for the Case

  • A core issue will be one of process definition: Can the negative limitation "without thermally treating the implant" be construed narrowly to mean only the specific, formal steps of "annealing" or "remelting," or does it have a broader scope that could encompass other heating steps present in the accused manufacturing process?
  • A key evidentiary question will be one of material properties: What technical evidence will be presented to prove or disprove that the accused E+ polyethylene possesses the specific quantitative characteristics—related to swelling, molecular weight, and gel content—required by the asserted claim of the '710 patent?
  • A third central question will concern knowledge and intent: What evidence demonstrates that Encore Medical had pre-suit knowledge of the patents and the infringing nature of its process, particularly for the patents issued after the DePuy litigation concluded, to support the claims of willful infringement?